What is Forensic Botany?
- Application of plant science to criminal and civil investigations
- Palynology: study of pollen and spores
- Dendrochronology: tree-ring dating
- Diatom analysis: aquatic forensic evidence
- Interdisciplinary field drawing from botany, ecology, law enforcement
- Why Plants Matter in Forensics…
- Provide evidence of movement, time, or location of crime
- Complement DNA, fingerprints, and traditional evidence
- Versatile, especially in outdoor scenes or missing person cases

Locard’s Exchange Principle
- “Every contact leaves a trace” – foundational forensic concept
- Botanical evidence at the scene: Plants, pollen, seeds, and soil samples found at a crime scene can be linked to a suspect if they are also found on the suspect’s clothing, shoes, or vehicle.
- Botanical evidence on the suspect:Conversely, plant material from the crime scene might be found on a suspect, indicating their presence at the location
- Establishing links: This exchange of botanical evidence can be crucial in linking a suspect to a crime scene or victim, especially when other forms of evidence are scarce.

Types of Botanical Evidence
- Macroscopic: Leaves, twigs, seeds, fruits, bark, wood
- Examples: Identifying a specific type of leaf found on a suspect’s clothing, analyzing plant material in a victim’s stomach to determine time of death, or presence of a plant species to link a suspect to a crime scene.
- Microscopic: Pollen, spores, diatoms, plant hairs (trichomes)
- Examples: dentifying the species of a pollen grain found on clothing or examining diatom assemblages to determine if a victim drowned in a specific body of water
- Each type tells a different story – location, season, transfer
- Macroscopic and microscopic analyses often complement each other, providing a more comprehensive understanding of the plant evidence
Types of Botanical Evidence

Botanical Evidence Basics: Macroscopic
- Look for unusual plant fragments at crime scenes - injuries (broken branches), or foreign species
- can links suspects with crime scenes
- experimenting with how long leaves on a broken branch take to wilt = timing
- Use ecology (flowering times, growth cycles etc.) of plants growing in/around body
- can determine timing of death (e.g. season)
- Plant identification can be crucial for determining if poisoning has occurred
- stomach contents, surrounding plants
- Seeds, burrs, and plant fragments adhere to shoes, tires, hair can reconstruct movement of people, vehicles, or bodies

Botanical Evidence Basics: Palynology
- Pollen & Spores - Pollen is unique by species, geographically distinct, and resists decay
- can be carried by wind, water, or animals, traveling far from their source
- individual grains of pollen from different species can look like soccer balls, sponges, padded cushions, or coffee beans
- surfaces are covered with intricate identifiable geometric patterns
- By examining pollen found at a crime scene or on a suspect, investigators can:
- potentially link individuals or objects to specific locations
- determine the time of year a crime occurred
- reconstruct events related to the crime

Palynology in Drug Trafficking
- In two different marijuana seizures in California and Texas, pollen analysis revealed a unique sagebrush pollen marker
- sagebrush species was known to grow in only a few isolated regions of Mexico + pinpointed the likely area where the marijuana was cultivated
- A truck carrying cocaine was seized at the Canadian border after attempting to enter from Detroit. Pollen analysis of the truck’s air filter revealed a pattern of pollen grains indicating the shipment originated in California and took a circuitous route across the United States instead of a direct path to Canada
- Pollen analysis also has helped CBP trace the routes of marijuana and cocaine bundles that wash up onshore along the coasts of Florida and Texas
- samples were loaded with fern spores, more than would be typical of an area where fern plants grow
- There are only a few areas that have that many ferns and one of them is Fern Gully, a winding, scenic stretch of road in Jamaica
Botanical Evidence Basics: Diatoms and Aquatic Evidence
- Diatoms are microscopic organisms that can be inhaled with water into the lungs
- If the individual was alive when they entered the water, diatoms will be found in the lungs and may circulate to other organs
- If the person was already dead, diatoms are less likely to be found
- Comparing the types and quantities of diatoms in a victim’s body with samples from potential drowning locations (like lakes, rivers, or oceans) can help establish where the drowning occurred
- Diatoms can also be transferred to clothing, footwear, or other personal items, potentially linking a suspect to a crime scene or a specific water source

Botanical Evidence Basics: Dendrochronology & Growth Clues
- Tree rings are used to date wood
- determine the age of wooden objects found at a crime scene
- growth over time around buried objects indicates timeline of burial
- climate records support or dispute timeline claims
- Certain plants bloom or fruit in predictable seasonal windows
- presence of specific plant structures can narrow time of crime
- ueful in matching or challenging suspect alibis

Botanical Evidence Basics: Plant-Based Toxins and Injuries
- Plants can cause injury or death: - Ricin from castor bean - Digitalis from foxglove - Coniine from hemlock
- Socrates who was sentenced to drink hemlock
- Abraham Lincoln’s mother due to white snakeroot
- Juan Ponce de León died after being wounded by an arrow poisoned with the manchineel tree’s sap
- Plant toxins can be used to prove a crime, such as homicide or theft, or to establish the cause of death in poisoning cases
- Forensic scientists use analytical techniques to identify and quantify plant toxins in biological samples (e.g., blood, urine, stomach contents)

Botanical Evidence Basics: Modern Technologies
- Stable Isotope Analysis - Measuring ratios of isotopes (C, N, O) in plants reflects regional climate or water and soil composition +can identify the source of illicit drugs or trace the origins of plants involved
- Example - Local climate controls stomatal openings. When stomata are forced to close (drought) they stop discriminating against heavy isotope (13C)
- Samples become more enriched in 13C compared to same species in an different climate

Its Time For A………
